Trouble Attaching eps Files to Review Comments

I am having a course I'm developing reviewed by the client. As they review, they want to attach .eps files to their comments on specific slides. They can occasionally attach a file, but often it fails to attach without any error. The same reviewer is able to attach .jpg files without issue. Anyone know what could be causing this or how to prevent it?

Client is running Windows 10 with the latest stable version of Chrome.